/**  
* DD_belatedPNG: Adds IE6 support: PNG images for CSS background-image and HTML <IMG/>.  
* Author: Drew Diller  
* Email: drew.diller@gmail.com  
* URL: http://www.dillerdesign.com/experiment/DD_belatedPNG/  
* Version: 0.0.7a  
* Licensed under the MIT License: http://dillerdesign.com/experiment/DD_belatedPNG/#license  
*  
* Example usage:  
* DD_belatedPNG.fix('.png_bg'); // argument is a CSS selector  
* DD_belatedPNG.fixPng( someNode ); // argument is an HTMLDomElement  
**/  
  
/*  
PLEASE READ:  
Absolutely everything in this script is SILLY.  I know this.  IE's rendering of certain pixels doesn't make sense, so neither does this code!  
*/  
  
var DD_belatedPNG = {   
  
    ns: 'DD_belatedPNG',   
    imgSize: {},   
       
    createVmlNameSpace: function() { /* enable VML */  
        if (document.namespaces && !document.namespaces[this.ns]) {   
          document.namespaces.add(this.ns, 'urn:schemas-microsoft-com:vml');   
        }   
        if (window.attachEvent) {   
            window.attachEvent('onbeforeunload', function() {   
                DD_belatedPNG = null;   
            });   
        }   
    },   
       
    createVmlStyleSheet: function() { /* style VML, enable behaviors */  
        /*  
            Just in case lots of other developers have added  
            lots of other stylesheets using document.createStyleSheet  
            and hit the 31-limit mark, let's not use that method!  
            further reading: http://msdn.microsoft.com/en-us/library/ms531194(VS.85).aspx  
        */  
        var style = document.createElement('style');   
        document.documentElement.firstChild.insertBefore(style, document.documentElement.firstChild.firstChild);   
        var styleSheet = style.styleSheet;   
        styleSheet.addRule(this.ns + '\\:*', '{behavior:url(#default#VML)}');   
        styleSheet.addRule(this.ns + '\\:shape', 'position:absolute;');   
        styleSheet.addRule('img.' + this.ns + '_sizeFinder', 'behavior:none; border:none; position:absolute; z-index:-1; top:-10000px; visibility:hidden;'); /* large negative top value for avoiding vertical scrollbars for large images, suggested by James O'Brien, http://www.thanatopsic.org/hendrik/ */  
        this.styleSheet = styleSheet;   
    },   
       
    readPropertyChange: function() {   
        var el = event.srcElement;   
        if (event.propertyName.search('background') != -1 || event.propertyName.search('border') != -1) {   
            DD_belatedPNG.applyVML(el);   
        }   
        if (event.propertyName == 'style.display') {   
            var display = (el.currentStyle.display == 'none') ? 'none' : 'block';   
            for (var v in el.vml) {   
                el.vml[v].shape.style.display = display;   
            }   
        }   
        if (event.propertyName.search('filter') != -1) {   
            DD_belatedPNG.vmlOpacity(el);   
        }   
    },   
       
    vmlOpacity: function(el) {   
        if (el.currentStyle.filter.search('lpha') != -1) {   
            var trans = el.currentStyle.filter;   
            trans = parseInt(trans.substring(trans.lastIndexOf('=')+1, trans.lastIndexOf(')')), 10)/100;   
            el.vml.color.shape.style.filter = el.currentStyle.filter; /* complete guesswork */  
            el.vml.image.fill.opacity = trans; /* complete guesswork */  
        }   
    },   
       
    handlePseudoHover: function(el) {   
        setTimeout(function() { /* wouldn't work as intended without setTimeout */  
            DD_belatedPNG.applyVML(el);   
        }, 1);   
    },   
       
    /**  
    * This is the method to use in a document.  
    * @param {String} selector - REQUIRED - a CSS selector, such as '#doc .container'  
    **/  
    fix: function(selector) {   
        var selectors = selector.split(','); /* multiple selectors supported, no need for multiple calls to this anymore */  
        for (var i=0; i<selectors.length; i++) {   
            this.styleSheet.addRule(selectors[i], 'behavior:expression(DD_belatedPNG.fixPng(this))'); /* seems to execute the function without adding it to the stylesheet - interesting... */  
        }   
    },   
       
    applyVML: function(el) {   
        el.runtimeStyle.cssText = '';   
        this.vmlFill(el);   
        this.vmlOffsets(el);   
        this.vmlOpacity(el);   
        if (el.isImg) {   
            this.copyImageBorders(el);   
        }   
    },   
       
    attachHandlers: function(el) {   
        var self = this;   
        var handlers = {resize: 'vmlOffsets', move: 'vmlOffsets'};   
        if (el.nodeName == 'A') {   
            var moreForAs = {mouseleave: 'handlePseudoHover', mouseenter: 'handlePseudoHover', focus: 'handlePseudoHover', blur: 'handlePseudoHover'};   
            for (var a in moreForAs) {   
                handlers[a] = moreForAs[a];   
            }   
        }   
        for (var h in handlers) {   
            el.attachEvent('on' + h, function() {   
                self[handlers[h]](el);   
            });   
        }   
        el.attachEvent('onpropertychange', this.readPropertyChange);   
    },   
       
    giveLayout: function(el) {   
        el.style.zoom = 1;   
        if (el.currentStyle.position == 'static') {   
            el.style.position = 'relative';   
        }   
    },   
       
    copyImageBorders: function(el) {   
        var styles = {'borderStyle':true, 'borderWidth':true, 'borderColor':true};   
        for (var s in styles) {   
            el.vml.color.shape.style[s] = el.currentStyle[s];   
        }   
    },   
       
    vmlFill: function(el) {   
        if (!el.currentStyle) {   
            return;   
        } else {   
            var elStyle = el.currentStyle;   
        }   
        for (var v in el.vml) {   
            el.vml[v].shape.style.zIndex = elStyle.zIndex;   
        }   
        el.runtimeStyle.backgroundColor = '';   
        el.runtimeStyle.backgroundImage = '';   
        var noColor = (elStyle.backgroundColor == 'transparent');   
        var noImg = true;   
        if (elStyle.backgroundImage != 'none' || el.isImg) {   
            if (!el.isImg) {   
                el.vmlBg = elStyle.backgroundImage;   
                el.vmlBg = el.vmlBg.substr(5, el.vmlBg.lastIndexOf('")')-5);   
            }   
            else {   
                el.vmlBg = el.src;   
            }   
            var lib = this;   
            if (!lib.imgSize[el.vmlBg]) { /* determine size of loaded image */  
                var img = document.createElement('img');   
                lib.imgSize[el.vmlBg] = img;   
                img.className = lib.ns + '_sizeFinder';   
                img.runtimeStyle.cssText = 'behavior:none; position:absolute; left:-10000px; top:-10000px; border:none;'; /* make sure to set behavior to none to prevent accidental matching of the helper elements! */  
                img.attachEvent('onload', function() {   
                    this.width = this.offsetWidth; /* weird cache-busting requirement! */  
                    this.height = this.offsetHeight;   
                    lib.vmlOffsets(el);   
                });   
                img.src = el.vmlBg;   
                img.removeAttribute('width');   
                img.removeAttribute('height');   
                document.body.insertBefore(img, document.body.firstChild);   
            }   
            el.vml.image.fill.src = el.vmlBg;   
            noImg = false;   
        }   
        el.vml.image.fill.on = !noImg;   
        el.vml.image.fill.color = 'none';   
        el.vml.color.shape.style.backgroundColor = elStyle.backgroundColor;   
        el.runtimeStyle.backgroundImage = 'none';   
        el.runtimeStyle.backgroundColor = 'transparent';   
    },   
       
    /* IE can't figure out what do when the offsetLeft and the clientLeft add up to 1, and the VML ends up getting fuzzy... so we have to push/enlarge things by 1 pixel and then clip off the excess */  
    vmlOffsets: function(el) {   
        var thisStyle = el.currentStyle;   
        var size = {'W':el.clientWidth+1, 'H':el.clientHeight+1, 'w':this.imgSize[el.vmlBg].width, 'h':this.imgSize[el.vmlBg].height, 'L':el.offsetLeft, 'T':el.offsetTop, 'bLW':el.clientLeft, 'bTW':el.clientTop};   
        var fudge = (size.L + size.bLW == 1) ? 1 : 0;   
           
        /* vml shape, left, top, width, height, origin */  
        var makeVisible = function(vml, l, t, w, h, o) {   
            vml.coordsize = w+','+h;   
            vml.coordorigin = o+','+o;   
            vml.path = 'm0,0l'+w+',0l'+w+','+h+'l0,'+h+' xe';   
            vml.style.width = w + 'px';   
            vml.style.height = h + 'px';   
            vml.style.left = l + 'px';   
            vml.style.top = t + 'px';   
        };   
        makeVisible(el.vml.color.shape, (size.L + (el.isImg ? 0 : size.bLW)), (size.T + (el.isImg ? 0 : size.bTW)), (size.W-1), (size.H-1), 0);   
        makeVisible(el.vml.image.shape, (size.L + size.bLW), (size.T + size.bTW), (size.W), (size.H), 1);   
           
        var bg = {'X':0, 'Y':0};   
        var figurePercentage = function(axis, position) {   
            var fraction = true;   
            switch(position) {   
                case 'left':   
                case 'top':   
                    bg[axis] = 0;   
                    break;   
                case 'center':   
                    bg[axis] = .5;   
                    break;   
                case 'right':   
                case 'bottom':   
                    bg[axis] = 1;   
                    break;   
                default:   
                    if (position.search('%') != -1) {   
                        bg[axis] = parseInt(position)*.01;   
                    }   
                    else {   
                        fraction = false;   
                    }   
            }   
            var horz = (axis == 'X');   
            bg[axis] = Math.ceil(fraction ? ( (size[horz?'W': 'H'] * bg[axis]) - (size[horz?'w': 'h'] * bg[axis]) ) : parseInt(position));   
            if (bg[axis] == 0) {   
                bg[axis]++;   
            }   
        };   
        for (var b in bg) {   
            figurePercentage(b, thisStyle['backgroundPosition'+b]);   
        }   
           
        el.vml.image.fill.position = (bg.X/size.W) + ',' + (bg.Y/size.H);   
           
        var bgR = thisStyle.backgroundRepeat;   
        var dC = {'T':1, 'R':size.W+fudge, 'B':size.H, 'L':1+fudge}; /* these are defaults for repeat of any kind */  
        var altC = { 'X': {'b1': 'L', 'b2': 'R', 'd': 'W'}, 'Y': {'b1': 'T', 'b2': 'B', 'd': 'H'} };   
        if (bgR != 'repeat') {   
            var c = {'T':(bg.Y), 'R':(bg.X+size.w), 'B':(bg.Y+size.h), 'L':(bg.X)}; /* these are defaults for no-repeat - clips down to the image location */  
            if (bgR.search('repeat-') != -1) { /* now let's revert to dC for repeat-x or repeat-y */  
                var v = bgR.split('repeat-')[1].toUpperCase();   
                c[altC[v].b1] = 1;   
                c[altC[v].b2] = size[altC[v].d];   
            }   
            if (c.B > size.H) {   
                c.B = size.H;   
            }   
            el.vml.image.shape.style.clip = 'rect('+c.T+'px '+(c.R+fudge)+'px '+c.B+'px '+(c.L+fudge)+'px)';   
        }   
        else {   
            el.vml.image.shape.style.clip = 'rect('+dC.T+'px '+dC.R+'px '+dC.B+'px '+dC.L+'px)';   
        }   
    },   
       
    fixPng: function(el) {   
        el.style.behavior = 'none';   
        if (el.nodeName == 'BODY' || el.nodeName == 'TD' || el.nodeName == 'TR') { /* elements not supported yet */  
            return;   
        }   
        el.isImg = false;   
        if (el.nodeName == 'IMG') {   
            if(el.src.toLowerCase().search(/\.png$/) != -1) {   
                el.isImg = true;   
                el.style.visibility = 'hidden';   
            }   
            else {   
                return;   
            }   
        }   
        else if (el.currentStyle.backgroundImage.toLowerCase().search('.png') == -1) {   
            return;   
        }   
        var lib = DD_belatedPNG;   
        el.vml = {color: {}, image: {}};   
        var els = {shape: {}, fill: {}};   
        for (var r in el.vml) {   
            for (var e in els) {   
                var nodeStr = lib.ns + ':' + e;   
                el.vml[r][e] = document.createElement(nodeStr);   
            }   
            el.vml[r].shape.stroked = false;   
            el.vml[r].shape.appendChild(el.vml[r].fill);   
            el.parentNode.insertBefore(el.vml[r].shape, el);   
        }   
        el.vml.image.shape.fillcolor = 'none'; /* Don't show blank white shapeangle when waiting for image to load. */  
        el.vml.image.fill.type = 'tile'; /* Ze magic!! Makes image show up. */  
        el.vml.color.fill.on = false; /* Actually going to apply vml element's style.backgroundColor, so hide the whiteness. */  
           
        lib.attachHandlers(el);   
           
        lib.giveLayout(el);   
        lib.giveLayout(el.offsetParent);   
           
        /* set up element */  
        lib.applyVML(el);   
    }   
       
};   
try {   
    document.execCommand("BackgroundImageCache", false, true); /* TredoSoft Multiple IE doesn't like this, so try{} it */  
} catch(r) {}   
DD_belatedPNG.createVmlNameSpace();   
DD_belatedPNG.createVmlStyleSheet(); 